High speed rotary switch with contact cleaning means



A. c. sTocKER ETAL 3,141,073

July 14, 1964 HIGH SPEED ROTARY SWITCH WITH CONTACT CLEANING MEANS Filed NOV. 25, 1960 3 Sheets-Sheet 1 INVENTORS Arfhur 6. Stacker Frpnk Wendze/ W////'am Ro/ke Karl 6. Kaufman ATTORNEY y 1964 A. c. STOCKER ETAL 3,141,073

HIGH SPEED ROTARY SWITCH WITH CONTACT CLEANING MEANS Filed Nov. 25, 1960 3 Sheets-Sheet 2 y 4, 1964 A. c. STOCKER ETAL 3,141,073

HIGH SPEED ROTARY SWITCH wz'm CONTACT CLEANING MEANS Filed NOV. 25, 1960 3 Sheets-Sheet 3 United States Patent Ofi ice 3,141,073 Patented July 14, 1964 3,141,073 HIGH SPEED ROTARY SWITCH WITH CONTACT CLEANING MEANS Arthur C. Stocker, Collingswood, N.J., Frank Wendzel, San Diego, Calif., and William Rolke, Merchantville, and Karl G. Kaufmann, Pensauken, N.J., assignors to the United States of America as represented by the Secretary of the Navy Filed Nov. 25, 1960, Ser. No. 71,847 Claims. (Cl. 200-24) This invention relates to electrical switches and more particularly to high speed rotary switches.

For a number of years, a need has been felt by industry for switches that will operate at high speeds-on the order of 1800 r.p.m.for long periods of time. Some switches of this type have been developed for telemetering service, but their life has been quite short-on the order of an 100 hourswhich makes them entirely inadequate for many uses.

A primary problem encountered in the development of a high speed rotary switch is the building up of a conductive film of carbon dust between the switch contacts to form a relatively low resistance path, permitting electrical leakage from contact to contact. This is a serious matter for many switch applications because these applications permit but very low leakage. Another problem encountered is the wear of the switch part because of friction.

To overcome these and other problems, this invention, among other things, provides apparatus whereby the friction is lessened through the use of materials having good characteristics as bearings whereby the deposition of carbon dust is minimized.

An object of this invention is to provide an improved rotary switch in which friction is lessened whereby wear is decreased and electrical contact is improved.

A further object is to provide improved apparatus to minimize the deposition of carbon dust on the switch contacts in a rotary switch whereby a low resistance path between contacts is avoided.

A still further object is to provide a switch of the above character which is simple, compact, reliable, and relatively inexpensive.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following de tailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a plan view with certain parts broken away showing the air current generating rotor, brushes, switch contacts and collecting slip ring;

FIG. 2 is a sectional view taken along line 2-2 in FIG. 1;

FIG. 3 illustrates a modified form of the switch and is a sectional view taken along line 3-3 of FIG. 4;

FIG. 4 is a sectional view taken generally along line 4-4 of FIG. 3; A

FIG. 5 is an enlarged sectional view of one of the air scoops taken along line 55 of FIG. 6;

FIG. 6 is an enlarged side view of one of the air scoops;

FIG. 7 is an enlarged plan view of one of the air scoops mounted on one of the brush carriers; and I FIG. 8 is an enlarged perspective view of one of the switch contacts of the switch shown in FIGS. Sand 4.

Referring to FIGS. 1 and 2, showing an embodiment of the invention, the switch 10 has contacts 12 supported in spaced condition, by screws 13 and slots 15, between two insulating members 14 and 16 in a circular configuration with the contact faces 12' toward the center of the circle. A collecting slip ring 18 is mounted by any suitable connection on the insulating member 16 radially inwardly of the contacts 12. Contacts 12 and collecting slip ring 18 are preferably made of a metallic substance, i.e., copper. A brush 20, for contacting contacts 12, and a brush 22, for cotacting the collecting slip ring 18, are mounted by brush carriers 24 and 26 on a shaft 28, which is rotatively supported in suitable bearings 30 and 32 by the insulating members 14 and 16. Brushes 20 and 22 are preferably constructed of a soft carbon material.

It will be understood that, as the brushes 20 and 22 rotate on the metallic contacts 12 and the collecting slip ring 18, carbon particles in the form of dust will be removed from the brushes by friction and can easily lodge in the spaces between contacts 12 causing wear and forming a relatively low resistance path, permitting electrical leakage from contact to contact. Since the contacts 12 must be separated by a very small gap in order to give the brush 20 a nearly smooth running path, and since the contacts 12 must be insulated from one another, the deposition of conductive dust between the contacts becomes a problem. To overcome this problem, in accordance with the apparatus of the present invention, air is blown through the gaps between the contacts 12 at such speed that the dust does not settle on the surface of the metal. An air current generating rotor indicated generally as 34 is mounted on shaft 28 for rotation therewith. Rotor 34 consists of a plate 36 which is secured to a collar 46 which is in turn fixed on shaft 28 by a suitable screw 47. Plate 36 has a portion 38 extending at right angles to the main plate portion and parallel to and spaced from the contacts 12. The portion 38 of plate 36 has a plurality of vanes or deflectors 40 formed at an acute angle to the portion 38. The portion 38 has an opening 42 therein to permit the extension of brush 20 therethrough. Likewise, plate 36 has an opening 44 therein to permit the extension of brush 22 therethrough.

It will be readily apparent that, as the shaft 28 rotates, the brushes 20 and 22 will contact the contacts 12 and collecting slip ring 18 and the vanes 40 of the rotor 34 will generate air currents directed toward the contacts 12 which will' blow any collected dust from between the contacts 12. i

It will be understood that, if the air current generating rotor of the present invention were placed in a rotary switch of conventional structure, the collection of dust on the insulating member on which the contacts are mounted would become a problem. In order to preventthe formation of a conductive film at the point where the contacts are mounted on the insulating member, it is necessary to either prevent the dusty air from striking the insulating member at this point or to provide a suificiently long surface on the insulating member such that the depo sition of the dust will be spread over a greater area and consequently the conduction will not be raised to an intolerable level. Insulating members 14 and 16, FIG. 2,. incorporate a combination of the above-noted solutions in that the insulating members are in contact with the contacts 12 only at the ends thereof leaving the greater part of the gap between the contacts free from obstruction; The vanes 40 are arranged generally at the center portion of the contacts 12 so that the main portion of the stream of dusty air will pass through the contacts gap between the insulating members '14 and 16 and consequently'the greater part of the dusty air will pass out of the switch without striking the insulating members 14 and 16. Further, the portions of insulating members 14 and 16 which are adjacent to the stream of dusty air are constructed of sufficient length so that the deposition of the dust will be spread over a considerable area so that the conduction is not raised to an intolerable level.

Referring to FIGS. 3 and 4, showing another embodiment of the invention, the contacts 112 have conical surfaces and are made up of alternate short contacts 112a and long contacts 112b. The contacts 112 are mounted on an insulating member 114 by any suitable connections. Long contacts 112!) are undercut as shown in FIGS. 3 and 8, leaving a space 1120 which acts as a flue to permit the dusty air to pass out of the switch and also provides a relatively long insulating surface sufliciently removed from the gap between the contacts 112 where dust enters so that the deposition of the dust on the insulating member will not raise the conduction to an intolerable level. A conical surface collecting slip ring 118 is also mounted on insulating member 114 inwardly of and offset from the contacts 112. A brush 120, for contacting the contacts 112, and a brush 122, for contacting the collecting slip ring 118, are mounted by brush carriers 124 and 126, respectively, on a shaft 128 which is rotatively supported in suitable bearings 130 by insulating member 116. Brush carriers 124 and 126 are mounted on a collar 132 which is secured to the shaft 128 by screws 134. The brush carriers 124 and 126 are offset laterally from the axis of the shaft 128 and are mounted at the same angle to a vertical plane taken along the transverse center line of the collar 132 as the angle of inclination 6', FIG. 8, of the conical surface of the contacts 112 and collecting slip ring 118.

In the form of the switch 110, shown in FlGS. 3 and 4, the air movement is caused by small scoops or deflectors, 136 mounted on the brush carriers 124 and 126. The air scoops 136 comprise a tapered bafile member 138, a pair of substantially triangular wings 140, integral with and at an acute angle to the tapered bafile member 138, and a mounting collar 142. The tapered baflle member 138 is secured to the mounting collar 142 by welding or any other suitable means as indicated at 144, at an acute angle to the longitudinal axis of the brush carriers 124;, 126 when mounted in operative position on said brush carriers. The mounting collar 142 is fixed to the brush carriers 124, 126 by the lock screw 146. The air scoops 136 are mounted on the same end of the brush carriers 124, 126 as the brushes 120 and 122, such that the air scoops 136 are spaced from the contacts 112 a suitable distance.

In operation, as the shaft 128 rotates, the brushes 120 and 122 move around the contacts 112 and collecting slip ring 118. At the same time, the air scoops 136 move with the brushes 120 and 122 to generate air currents which are directed toward the contacts 112 to blow dust from the said contacts. The air currents will prevent the build up of a conductive film between the contacts and the leakage will therefore be minimized.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that Within the scope of the appended claims the invention may be practiced otherwise than is specifically described.

What is claimed is:

1. In a switch having a housing, said housing comprising a first and second spaced insulating member, contact means fixed to said second insulating member in a circular configuration, a collecting slip ring mounted within said second insulating member, rotating brush means contacting said contact means and said collecting slip ring, said brush means including brush carriers, and air scoops mounted on said brush carriers, said air scoops comprising a baffle member offset from the longitudinal axis of said brsuh carriers and being mounted at an acute angle relative thereto.

2. In a high speed rotary switch, a switch housing comprising first and second spaced insulating means, a ring of spaced metallic contacts mounted on at least one of said first and second insulating members and extending therebetween, a shaft journaled for rotation in said insulating members within said ring of metallic contacts, a metallic collecting slip ring mounted on said first insulating member between said metallic contacts and said shaft, first and second brush carriers fixedly mounted on said shaft for rotary movement therewith, a first soft carbon brush mounted on said first brush carrier and contacting said metallic contacts, a second soft carbon brush mounted on said second brush carrier and contacting said collecting slip ring, and deflecting means mounted in juxtaposition to said brush carriers for movement therewith to generate air currents directed toward said contacts for removing carbon dust particles from said contacts.

3. The switch as set forth in claim 2, wherein said air deflecting means comprise a baflle member offset from and at an acute angle to the longitudinal axis of said brush carriers.

4. The switch as set forth in claim 2, wherein the air deflector means comprises a plate member having angled vanes in its outer surface.

5. In a high speed rotary switch, a switch housing comprising first and second spaced insulating members, a plurality of spaced air inlets in said first insulating member, a centrally located aperture in each of said insulating members, said insulating members having a. plurality of equally spaced apertures about their circumference, a ring of spaced metallic contacts mounted on said first insulating member and being received by said second insulating member, a shaft journaled for rotation in said centrally located apertures, said ring of metallic contacts being located radially inward of the spaced apertures in said insulating member, a metallic collecting slip ring mounted on said second insulating member, said collecting slip ring concentrically positioned with respect to said shaft and said metallic contacts, first and second brush carriers fixedly mounted on said shaft for rotary movement therewith, a first soft carbon brush mounted on said first brush carrier and contacting said metallic contacts, a second soft carbon brush mounted on said second brush carrier and contacting said collecting slip ring, air deflecting means mounted in juxtaposition to said brush carriers for movement therewith whereby rotation of said shaft rotates said air deflecting means, drawing air in through said air inlet and generating air currents directed toward said contacts over a full 360 degrees of rotation thus forcing air between said contacts permitting the air to exit via said apertures in said first and second insulating members which are in alignment with said contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,217,566 Cavanagh Feb. 27, 1917 1,356,532 Lang Oct. 26, 1920 1,411,073 Werner Mar. 28, 1922 1,813,808 Kuehn July 7, 1931 2,107,709 Oberdick Feb. 8, 1938 2,207,368 Arthur July 9, 1940 2,251,387 Arthur Aug. 5, 1941 2,518,628 MacIntyre Aug. 15, 1950 2,652,471 Harada Sept. 15, 1953 FOREIGN PATENTS 177,392 Great Britain Mar. 30, 1922 288,410 Great Britain Apr. 12, 1928 312,002 Germany M May 9, 1919 518,252 Germany Feb. 13, 1931 

1. IN A SWITCH HAVING A HOUSING, SAID HOUSING COMPRISING A FIRST AND SECOND SPACED INSULATING MEMBER, CONTACT MEANS FIXED TO SAID SECOND INSULATING MEMBER IN A CIRCULAR CONFIGURATION, A COLLECTING SLIP RING MOUNTED WITHIN SAID SECOND INSULATING MEMBER, ROTATING BRUSH MEANS CONTACTING SAID CONTACT MEANS AND SAID COLLECTING SLIP RING, SAID BRUSH MEANS INCLUDING BRUSH CARRIERS, AND AIR SCOOPS MOUNTED ON SAID BRUSH CARRIERS, SAID AIR SCOOPS COMPRISING A BAFFLE MEMBER OFFSET FROM THE LONGITUDINAL AXIS OF SAID BRUSH CARRIERS AND BEING MOUNTED AT AN ACUTE ANGLE RELATIVE THERETO. 